Estevan Payan Strikeforce and UFC veteran Isaac Vallie-Flagg suffered an elbow injury which has forced him out of his WSOF 23 preliminary bout with Estavan Payan . Replacing Vallie-Flagg (15-7-1) in the lightweight bout will be Kamuela Kirk (4-1). The change was announced in a press release from the promotion. WSOF 23 takes place Sept